Elemental sulfur is widely used in the agricultural and chemical industries as a soil amendment, with or without other components, as a chemical precursor (sulfuric acid) and as a compound in elastomeric, paint, road surface and structural material formulations.
The present invention involves the improvement of several sulfur properties, particularly those properties that influence agronomic use, compounding or formulation with hydrophobic materials, and general ease and safety of transport and handling. Relevant properties include grindability, particle fluidity, bridging in process or transport equipment, water retention, and resistance to oxidation and corrosion.
These compositions comprise homogeneous distributions of certain hydrocarbons in an elemental sulfur matrix. They may or may not contain other components as desired. The oil is distributed evenly throughout a continuous sulfur matrix. This property provides a predetermined hydrocarbon-sulfur ratio regardless of grinding, or particle consumption in use. It allows for higher hydrocarbon loadings and reduced surface cohesiveness at high loading and reduces agglomeration and bridging.
In these and other respects these compositions are superior to other hydrocarbon-sulfur combinations suggested in the prior art. For instance, Block U.S. Pat. No. 3,661,530 suggests that several deficiencies of dusting sulfur can be minimized by post manufacture surface application of a variety of hydrocarbon compounds. Block was concerned primarily with fluidity (sulfurs that remain free-flowing) and agglomeration or anti-caking qualities which are known problems with finely divided sulfurs.
Undoubtedly Block's procedures reduce the magnitude of these problems. However, I have found that surface application has several disadvantages. Only a limited amount of hydrocarbon can be retained on the particle surface, and even less than this limit should be added to avoid agglomeration (depending on hydrocarbon properties and conditions of use). Excess hydrocarbon which is tacky during use will itself cause agglomeration and the problems which Block seeks to avoid. More importantly, the continuous sulfur-hydrocarbon interface will persist only so long as the particles are not further comminuted, degraded or consumed during use by bacterial action, grinding, or high shear blending. Any of these common occurrences will expose uncoated surfaces.
In contrast, the compositions of this invention do not suffer the same deficiencies. Particles obtained by fracturing larger particles or blocks still contain hydrocarbon disposed throughout the sulfur matrix since, in the first instance, the hydrocarbon is not simply coated on the exterior surface of the block, particle, etc., or contained in some coating that covers only the particle or block surface. Thus, no matter how small the blocks or particles are ground by any procedure, the resulting particles and dust contain the amount of hydrocarbon desired.